JP2011181234A - Nonaqueous electrolyte type lithium ion secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lithium ion secondary battery which has less capacity degradation due to rapid discharge. <P>SOLUTION: The lithium ion secondary battery includes positive and negative electrodes that can occlude and release lithium ions, and a nonaqueous electrolyte. The nonaqueous electrolyte comprises at least a lithium salt as a support salt in an organic solvent and further comprises 0.02 to 4 mmol of a compound represented by formula (I) as an additive, on the basis of the total weight of 100 g of those electrolyte components. Each of R<SB>1</SB>to R<SB>3</SB>in formula (I), independently represents a 1-4C perfluoroalkyl group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lithium ion secondary battery having excellent discharge rate characteristics.

  A lithium ion secondary battery includes positive and negative electrodes capable of reversibly occluding and releasing lithium ions, and an electrolyte interposed between the two electrodes, and the lithium ions in the electrolyte travel between the electrodes. To charge and discharge. Because it is lightweight and has high energy density, it is used as a power source for various portable devices. In addition, use in vehicles and other applications that require a large-capacity power source has been studied, and further improvement in battery performance is required. Patent documents 1 and 2 are mentioned as technical literature about the performance improvement of a lithium ion secondary battery.

JP 2008-137799 A JP 2004-296095 A

  The discharge performance (for example, discharge capacity) of a lithium ion secondary battery can vary greatly depending on the discharge rate even for the same battery. Usually, the discharge capacity tends to decrease rapidly as the rate increases. In recent years, various lithium ion secondary batteries for vehicles have been studied. Regarding performance (discharge rate characteristics, etc.) that can withstand discharge at a high rate (rapid discharge) as required for power sources for vehicles, There is a need for further performance improvements.

  An object of the present invention is to provide a lithium ion secondary battery with improved discharge capacity during rapid discharge and excellent discharge rate characteristics.

  The present inventor has found that the use of a predetermined additive suppresses a decrease in capacity during rapid discharge, and has completed the present invention.

で表される化合物Ｉ０．０２ｍｍｏｌ〜４ｍｍｏｌを更に含む。上記式（Ｉ）中のＲ_１〜Ｒ_３は、それぞれ独立に炭素数１〜４のパーフルオロアルキル基である。パーフルオロアルキル基とは、Ｈが全てＦに置換されたアルキル基を意味する。
上記添加剤を含む組成の電解液によると、初期内部抵抗（反応抵抗）を比較的低く抑え、急速放電時にも低速放電時により近い放電容量を発揮するリチウムイオン二次電池が実現され得る。換言すれば、リチウムイオン二次電池の放電レート特性を向上することができる。これにより、急速放電時の容量低下を抑制することができる。したがって、かかる組成の電解液によると、急速放電によりよく対応し得る放電レート特性を備えたリチウムイオン二次電池が提供され得る。 According to the present invention, a lithium ion secondary battery including positive and negative electrodes capable of inserting and extracting lithium ions and a nonaqueous electrolytic solution is provided. The non-aqueous electrolyte contains at least a lithium salt as a supporting salt in an organic solvent, and the following formula (I) is used as an additive with respect to a total amount of 100 g of these electrolyte constituents:

In addition, 0.02 mmol to 4 mmol of the compound I represented by R _{1 to} R ₃ in the above formula (I) are each independently a perfluoroalkyl group having 1 to 4 carbon atoms. A perfluoroalkyl group means an alkyl group in which all of H is substituted with F.
According to the electrolytic solution having the composition containing the additive, a lithium ion secondary battery can be realized in which the initial internal resistance (reaction resistance) is kept relatively low and a discharge capacity closer to that at the time of low speed discharge is exhibited even during rapid discharge. In other words, the discharge rate characteristics of the lithium ion secondary battery can be improved. Thereby, the capacity | capacitance fall at the time of rapid discharge can be suppressed. Therefore, according to the electrolytic solution having such a composition, it is possible to provide a lithium ion secondary battery having a discharge rate characteristic that can better cope with rapid discharge.

In a preferred embodiment of the lithium ion secondary battery disclosed herein, R _{1 to} R ₃ in the above formula are all trifluoromethyl groups. Thereby, a lithium ion secondary battery in which capacity deterioration during rapid discharge is further suppressed can be formed.

  According to the technology disclosed herein, as described above, a lithium ion secondary battery with little reduction in capacity even when discharged at a high rate can be realized. Such a battery is suitable as a vehicle-mounted battery in which rapid discharge can occur during normal use. Therefore, according to this invention, the vehicle provided with one of the lithium ion secondary batteries disclosed here is provided. In particular, a vehicle (for example, an automobile) including such a lithium ion secondary battery as a power source (typically, a power source of a hybrid vehicle or an electric vehicle) is preferable.

It is a perspective view which shows typically the external shape of the lithium ion secondary battery which concerns on one Embodiment. It is the II-II sectional view taken on the line in FIG. It is a side view which shows typically the vehicle (automobile) provided with the lithium ion secondary battery of this invention. It is a fragmentary sectional view showing typically a coin type battery produced in an example.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field.

  The lithium ion secondary battery disclosed herein includes an electrode body having a positive electrode and a negative electrode capable of inserting and extracting lithium ions, a lithium salt as a supporting salt, and a compound represented by the above formula (I) as an additive A non-aqueous electrolyte solution containing an organic solvent (non-aqueous solvent).

As the supporting salt contained in the nonaqueous electrolytic solution, a lithium salt used as a supporting salt in a general lithium ion secondary battery can be appropriately selected and used. Examples of the lithium salt include LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , Li (CF ₃ SO ₂ ) ₂ N, LiCF ₃ SO _{3 and the} like. These supporting salts can be used alone or in combination of two or more. A particularly preferred example is LiPF ₆ . The nonaqueous electrolytic solution is preferably prepared so that the concentration of the supporting salt is within a range of 0.7 to 1.6 mol / L, for example.

  As said non-aqueous solvent, the organic solvent used for a general lithium ion secondary battery can be selected suitably, and can be used. Particularly preferred non-aqueous solvents include carbonates such as ethylene carbonate (EC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and propylene carbonate (PC). These organic solvents can be used alone or in combination of two or more.

As said additive, the compound I represented by the said formula (I) can be used individually by 1 type or in combination of 2 or more types.
Here, R < ₁ > -R < ₃ > is a C1-C4 perfluoroalkyl group each independently. The alkyl group may be either linear or branched, but is typically linear. Specific examples of the perfluoroalkyl _{group, -CF 3, -CF 2 CF 3} , - (CF 2) 2 CF 3, - (CF 2) 3 CF 3 and the like. As a particularly preferred example of compound I, compound II represented by the following formula (II) can be mentioned.

  The total amount of the additive contained in the non-aqueous electrolyte may be in the range of about 0.02 mmol to 4 mmol with respect to 100 g of the total amount of other electrolyte components (that is, components other than the additive). preferable. For example, when Compound II is used as the additive, this addition amount corresponds to the inclusion of the additive in the range of 0.01 g to 2 g with respect to 100 g of the electrolyte component other than the additive. When the amount is less than the above range, the effect of suppressing the capacity drop during rapid discharge may not be sufficient. On the other hand, if it is more than the above range, the discharge rate characteristics (particularly the capacity during rapid discharge) and the cycle characteristics may deteriorate.

In carrying out the present invention, it is not necessary to elucidate the mechanism by which the rapid discharge performance (for example, discharge rate characteristics) is improved by the additive, but the following may be considered.
Usually, when a non-aqueous electrolyte containing a carbonate-based solvent as described above is used, a part of the electrolyte components (solvent, supporting salt, etc.) undergoes reductive decomposition during initial charging, and the negative electrode surface is decomposed from the decomposition product. It is covered with a SEI (Solid Electrolyte Interface) film. This can prevent further reductive decomposition of the electrolyte component on the negative electrode surface during normal use of the battery. On the other hand, in the battery of this mode, the internal resistance may increase on the contrary depending on the composition and film thickness of the formed SEI film. In particular, the increase in internal resistance becomes significant during rapid discharge. However, when a small amount of the above additive is added to the non-aqueous electrolyte as described above, the decomposition product of the additive improves the characteristics of the SEI membrane (such as lithium ion conductivity) and suppresses an increase in reaction resistance. Can do. As a result, a lithium ion secondary battery having excellent discharge rate characteristics with little reduction in capacity even during rapid discharge can be formed. For example, when the compound II is used as such an additive, the characteristics of the SEI film can be further improved, and the capacity reduction can be more gradual.

  Hereinafter, a lithium ion secondary battery 100 (FIG. 1) in an embodiment in which an electrode body and a nonaqueous electrolytic solution are housed in a rectangular battery case with respect to the lithium ion secondary battery according to the present invention will be described with reference to the drawings. This will be described in more detail by way of example, but is not intended to limit the present invention to such an embodiment. That is, the shape of the lithium ion secondary battery according to the present invention is not particularly limited, and the battery case, electrode body, and the like can be appropriately selected in terms of material, shape, size, and the like according to the application and capacity. For example, the battery case may have a rectangular parallelepiped shape, a flat shape, a cylindrical shape, or the like. In addition, in the following drawings, the same code | symbol is attached | subjected to the member and site | part which show | plays the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

  As shown in FIGS. 1 and 2, the battery 100 according to the present embodiment includes a wound electrode body 20 and a flat box-shaped battery case 10 corresponding to the shape of the electrode body 20 together with an electrolyte solution (not shown). It can be constructed by being housed inside the opening 12 and closing the opening 12 of the case 10 with a lid 14. The lid body 14 is provided with a positive terminal 38 and a negative terminal 48 for external connection so that a part of the terminals protrudes to the surface side of the lid body 14.

  The electrode body 20 includes a positive electrode sheet 30 in which a positive electrode active material layer 34 is formed on the surface of a long sheet-like positive electrode current collector 32, and a negative electrode active material layer on the surface of a long sheet-like negative electrode current collector 42. The negative electrode sheet 40 on which the electrode 44 is formed is rolled up with two long sheet-like separators 50, and the obtained wound body is crushed from the side surface and ablated to form a flat shape. ing.

  Further, the positive electrode sheet 30 is formed such that the positive electrode active material layer 34 is not provided (or removed) at one end along the longitudinal direction, and the positive electrode current collector 32 is exposed. Similarly, the negative electrode sheet 40 to be wound is not provided with (or removed from) the negative electrode active material layer 44 at one end along the longitudinal direction so that the negative electrode current collector 42 is exposed. Is formed. Then, the positive electrode terminal 38 is joined to the exposed end portion of the positive electrode current collector 32, and the negative electrode terminal 48 is joined to the exposed end portion of the negative electrode current collector 42, respectively. The positive electrode sheet 30 or the negative electrode sheet 40 is electrically connected. The positive and negative terminals 38 and 48 and the positive and negative current collectors 32 and 42 can be joined by, for example, ultrasonic welding, resistance welding, or the like.

  The positive electrode active material layer 34 includes, for example, a paste or slurry composition (positive electrode mixture) in which a positive electrode active material is dispersed in an appropriate solvent together with a conductive material, a binder (binder), and the like as necessary. It can preferably be produced by applying to the positive electrode current collector 32 and drying the composition.

As the positive electrode active material, a material capable of reversibly occluding and releasing lithium is used, and one or two of materials conventionally used in lithium ion secondary batteries (for example, oxides having a layered structure or oxides having a spinel structure) are used. More than one species can be used without any particular limitation. Examples thereof include lithium-containing composite oxides such as lithium nickel composite oxides, lithium cobalt composite oxides, lithium manganese composite oxides, and lithium magnesium composite oxides.
Here, the lithium nickel-based composite oxide is an oxide having lithium (Li) and nickel (Ni) as constituent metal elements, and at least one other metal element (that is, Li and nickel) in addition to lithium and nickel. An oxide containing a transition metal element other than Ni and / or a typical metal element) as a constituent metal element at a rate equivalent to or less than nickel in terms of the number of atoms (typically less than nickel) It means to include. Examples of the metal element other than Li and Ni include, for example, cobalt (Co), aluminum (Al), manganese (Mn), chromium (Cr), iron (Fe), vanadium (V), magnesium (Mg), and titanium (Ti ), Zirconium (Zr), niobium (Nb), molybdenum (Mo), tungsten (W), copper (Cu), zinc (Zn), gallium (Ga), indium (In), tin (Sn), lanthanum (La) And one or more metal elements selected from the group consisting of cerium (Ce). The same meaning applies to lithium cobalt complex oxides, lithium manganese complex oxides, and lithium magnesium complex oxides.
Further, an olivine type lithium phosphate represented by the general formula LiMPO ₄ (M is at least one element of Co, Ni, Mn, and Fe; for example, LiFePO ₄ , LiMnPO ₄ ) is used as the positive electrode active material. Also good.
The amount of the positive electrode active material contained in the positive electrode mixture can be selected as appropriate, and can be, for example, about 80 to 95% by mass.

As the conductive material, a conductive powder material such as carbon powder or carbon fiber is preferably used. As the carbon powder, various carbon blacks such as acetylene black, furnace black, ketjen black, and graphite powder are preferable. A conductive material can be used alone or in combination of two or more.
What is necessary is just to select suitably the quantity of the electrically conductive material contained in a positive electrode compound material according to the kind and quantity of a positive electrode active material, for example, can be about 4-15 mass%.

As the binder, for example, a water-soluble polymer that dissolves in water, a polymer that disperses in water, a polymer that dissolves in a non-aqueous solvent (organic solvent), and the like can be appropriately selected and used. Moreover, only 1 type may be used independently and 2 or more types may be used in combination.
Examples of the water-soluble polymer include carboxymethylcellulose (CMC), methylcellulose (MC), cellulose acetate phthalate (CAP), hydroxypropylmethylcellulose (HPMC), hydroxypropylmethylcellulose phthalate (HPMCP), and polyvinyl alcohol (PVA). It is done.
Examples of the water-dispersible polymer include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and ethylene-tetra. Fluorine resin such as fluoroethylene copolymer (ETFE), vinyl acetate copolymer, styrene butadiene block copolymer (SBR), acrylic acid-modified SBR resin (SBR latex), rubbers such as gum arabic, etc. It is done.
Examples of the polymer dissolved in the non-aqueous solvent (organic solvent) include, for example, polyvinylidene fluoride (PVDF), polyvinylidene chloride (PVDC), polyethylene oxide (PEO), polypropylene oxide (PPO), and polyethylene oxide-propylene oxide copolymer. (PEO-PPO) and the like.
What is necessary is just to select the addition amount of a binder suitably according to the kind and quantity of a positive electrode active material, for example, can be about 1-5 mass% of the said positive electrode compound material.

  For the positive electrode current collector 32, a conductive member made of a metal having good conductivity is preferably used. For example, aluminum or an alloy containing aluminum as a main component can be used. The shape of the positive electrode current collector 32 may vary depending on the shape of the lithium ion secondary battery, and is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. . In the present embodiment, a sheet-like aluminum positive electrode current collector 32 is used, and can be preferably used for the lithium ion secondary battery 100 including the wound electrode body 20. In such an embodiment, for example, an aluminum sheet having a thickness of about 10 μm to 30 μm can be preferably used.

  The negative electrode active material layer 44 includes, for example, a negative electrode current collector 42 made of a paste or slurry composition (negative electrode mixture) in which a negative electrode active material is dispersed in an appropriate solvent together with a binder (binder) and the like. And the composition can be preferably prepared by drying.

As the negative electrode active material, one type or two or more types of materials conventionally used in lithium ion secondary batteries can be used without any particular limitation. For example, a carbon particle is mentioned as a suitable negative electrode active material. A particulate carbon material (carbon particles) containing a graphite structure (layered structure) at least partially is preferably used. Any carbon material of a so-called graphitic material (graphite), non-graphitizable carbon material (hard carbon), easily graphitized carbon material (soft carbon), or a combination of these materials is preferably used. obtain. Among these, graphite particles such as natural graphite can be preferably used. Since the graphite particles can suitably occlude lithium ions as charge carriers, they are excellent in conductivity. Moreover, since the particle size is small and the surface area per unit volume is large, it can be a negative electrode active material more suitable for rapid charge / discharge (for example, high output discharge).
The amount of the negative electrode active material contained in the negative electrode mixture is not particularly limited, but is preferably about 90 to 99% by mass, more preferably about 95 to 99% by mass.

  As the binder, the same positive electrode as that described above can be used alone or in combination of two or more. What is necessary is just to select the addition amount of a binder suitably according to the kind and quantity of a negative electrode active material, for example, can be about 1-5 mass% of a negative electrode compound material.

  As the negative electrode current collector 42, a conductive member made of a metal having good conductivity is preferably used. For example, copper or an alloy containing copper as a main component can be used. In addition, the shape of the negative electrode current collector 42 may vary depending on the shape of the lithium ion secondary battery and the like, and thus is not particularly limited, and may be various forms such as a rod shape, a plate shape, a sheet shape, a foil shape, and a mesh shape. possible. In the present embodiment, a sheet-like copper negative electrode current collector 42 is used, and can be preferably used for the lithium ion secondary battery 100 including the wound electrode body 20. In this embodiment, for example, a copper sheet having a thickness of about 5 μm to 30 μm can be preferably used.

  The separator 50 is a sheet interposed between the positive electrode sheet 30 and the negative electrode sheet 40, and is disposed so as to be in contact with the positive electrode active material layer 34 of the positive electrode sheet 30 and the negative electrode active material layer 44 of the negative electrode sheet 40. Is done. Then, prevention of short circuit due to the contact between the electrode active material layers 34 and 44 in the positive electrode sheet 30 and the negative electrode sheet 40, and the conduction path between the electrodes (conductive path) by impregnating the electrolyte in the pores of the separator 50. ). As a constituent material of the separator 50, a porous sheet (microporous resin sheet) made of a resin can be preferably used. Porous polyolefin resins such as polyethylene (PE), polypropylene (PP), and polystyrene are preferred. In particular, a PE sheet, a PP sheet, a two-layer structure sheet in which a PE layer and a PP layer are laminated, and the like can be suitably used. The thickness of the separator is preferably set within a range of approximately 10 μm to 40 μm, for example.

  Several examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In the following description, “parts” and “%” are based on mass unless otherwise specified.

[Production of battery]
<Example 1>
As a positive electrode mixture, 125 mL of an N-methylpyrrolidone (NMP) solution containing 5 g of PVDF as a binder, 85 g of LiCoO ₂ (theoretical discharge capacity 275 mAh / g) powder as a positive electrode active material, and acetylene black as a conductive material 10 g was added and kneaded until uniform to prepare a paste-like composition. This positive electrode mixture was applied to one surface of an aluminum foil (positive electrode current collector) having a thickness of 15 μm so that the application amount was 6.5 mg / cm ² (based on solid content). This was dried and pressed to obtain a positive electrode sheet.

As a negative electrode mixture, 92.5 g of graphite was added to 125 mL of NMP solution containing 7.5 g of PVDF (binder), and kneaded until uniform to prepare a paste-like composition. This negative electrode mixture was applied to one side of a 15 μm-thick copper foil (negative electrode current collector) so that the coating amount was 4.3 mg / cm ² (solid content basis). This was dried and pressed to obtain a negative electrode sheet.

The non-aqueous electrolyte is 0.01 g (0.02 mmol; hereinafter referred to as such addition amount) with respect to 100 g of a solution containing LiPF ₆ at a concentration of 1 mol / L in a mixed solvent of EC and DEC (volume ratio 3: 7). Was prepared by adding Compound II of 0.02 mmol / 100 g).
As a separator, a polypropylene (PP) porous film having a thickness of 25 μm was prepared and impregnated with the electrolytic solution.

  Using these battery members, a 2032 coin cell 200 (FIG. 4) was produced. That is, the positive electrode sheet 30 and the negative electrode sheet 40 cut out to appropriate sizes were laminated together with the separator 50 impregnated with the electrolytic solution and accommodated in a coin-type container 80 (negative electrode terminal). The non-aqueous electrolyte was poured into this container, and the container was sealed with a gasket 60 and a lid 70 (positive electrode terminal) to obtain a battery according to Example 1.

<Example 2>
A battery according to Example 2 was obtained in the same manner as Example 1 except that the amount of Compound II added was changed to 0.5 g (1 mmol / 100 g).
<Example 3>
A battery according to Example 3 was obtained in the same manner as Example 1 except that the amount of Compound II added was 1 g (2 mmol / 100 g).
<Example 4>
A battery according to Example 4 was obtained in the same manner as Example 1 except that the amount of Compound II added was 2 g (4 mmol / 100 g).
<Example 5>
A battery according to Example 5 was obtained in the same manner as in Example 1, except that the amount of Compound II added was 5 g (9.8 mmol / 100 g).
<Example 6>
A battery according to Example 6 was obtained in the same manner as in Example 1 except that Compound II was not added.

[Initial charging process]
For each of the obtained batteries of Examples 1 to 6, an operation of charging to 4.1 V at a rate of 1/10 C at a temperature of 25 ° C. and an operation of discharging to 3.0 V at the same rate were alternately performed 3 Repeated times. Next, constant current constant voltage charging was performed in which charging was performed at a rate of 1 C until the voltage reached 4.1 V, and then charging was performed at 4.1 V for 2 hours.

[Measurement of reaction resistance]
For each of the batteries of Examples 1 to 6 after the initial charging, the measurement frequency was swept to perform AC impedance measurement, and the reaction resistance (mΩ) was read from the Cole-Cole plot of the obtained impedance (Z). These results are shown in Table 1 together with the amount of Compound II added (mmol / 100 g).

[Discharge rate characteristics]
For each battery of Examples 1 to 6 obtained in the same manner, after initial charging as described above to a voltage of 4.1 V, at each rate of 0.3C, 1C, 5C, 10C, 15C, and 20C, A constant current was discharged until the voltage reached 3 V, and the discharge capacity at that time was measured. The discharge capacity at 0.3 C is assumed to be 100, and the ratio of discharge capacity at each rate relative to this is also shown in Table 1.

[Charge / discharge cycle characteristics]
Each battery of Examples 1 to 6 obtained in the same manner was charged at a constant current rate at a temperature of 25 ° C. until the voltage reached 4.1 V, and then charged at 4.1 V for 1.5 hours. This operation was performed 100 cycles, with the operation to perform and the operation to discharge to 3 V at the same rate as one charge / discharge cycle. Before and after the cycle test, each battery was discharged at a temperature of 25 ° C. at a rate of 1 C until the voltage became 3 V, and the discharge capacity at this time was measured. The capacity retention rate (%) after the cycle test was determined as a percentage of the discharge capacity after the test with respect to the discharge capacity before the test. These results are also shown in Table 1.

  As shown in Table 1, the batteries 1 to 4 having an addition amount of Compound II of 0.02 mmol to 4 mmol / 100 g are compared with the battery 5 having an addition amount of 9.8 mmol / 100 g and the battery 6 to which no compound II is added. The reaction resistance was kept low, and the discharge capacity reduction at a discharge rate exceeding 10 C was suppressed to a higher degree. In addition, a high capacity retention rate of approximately 90% was exhibited even after the cycle test. In particular, even when the battery 2 was discharged at a high rate of 15 C, the capacity decrease was relatively small.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 1 Vehicle 20 Winding electrode body 30 Positive electrode sheet 32 Positive electrode collector 34 Positive electrode active material layer 38 Positive electrode terminal 40 Negative electrode sheet 42 Negative electrode collector 44 Negative electrode active material layer 48 Negative electrode terminal 50 Separator 100, 200 Lithium ion secondary battery

Claims (3)

A lithium ion secondary battery comprising positive and negative electrodes capable of inserting and extracting lithium ions and a non-aqueous electrolyte,
The non-aqueous electrolytic solution contains at least a lithium salt as a supporting salt in an organic solvent, and the following formula (I):

A lithium ion further containing 0.02 mmol to 4 mmol of a compound represented by the formula (wherein R _{1 to} R ₃ in the formula (I) are each independently a C ₁ to C 4 perfluoroalkyl group): Secondary battery. 2. The lithium ion secondary battery according to claim 1, wherein R _{1 to} R ₃ in the formula (I) are all —CF ₃ .   A vehicle comprising the lithium ion secondary battery according to claim 1.

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